Ambient Air Monitoring for the Revised Lead NAAQS

Daniel Garver

US EPA Region 4

Overview

• On October 15, 2008, EPA strengthened the national ambient air quality standards (NAAQS) for lead (Pb).– Since 1978, lead standards have been set at 1.5

μg/m3

– Now, EPA is strengthening the lead standards by 90 percent to a level of 0.15 μg/m3.

– The level is based on the concentration of lead in total suspended particles (TSP)

– EPA is also making changes to the lead monitoring network to ensure monitors are assessing air quality in areas that might violate the new standard.

NAAQS Averaging Time and Form: Old vs. New NAAQS

• Both specified as “not be exceeded” maximum 3-month average

• Both require 1 in 6 day sampling frequency• Old NAAQS based on calendar quarters; new NAAQS

based on “rolling” 3-month averages• Also, the 3-month averages (for Old versus New) are

calculated slightly different• Data handling details in 40 CFR 50 Appendix R

• NAAQS evaluation period handled differently– Old NAAQS had 1-year “look” for designations and 2-year

evaluation period for redesignations– New NAAQS will use 3-year look for original designations and

also redesignations

NAAQS Averaging TimeOld vs. New

Lead Monitoring Requirements

• Lead monitoring required:– At sources emitting 1.0 tpy or more of Pb based on

NEI or other justifiable data.– In core-based statistical areas (CBSAs) with

population over 500,000.• Approx. 48 total required monitors in Region 4• Approx. 22 source-oriented monitors must be

identified in Network Plans and installed by 1/1/2010

• Monitors must be sited for max concentration, taking into account logistics and the potential for population exposure.

MAP

Source-Oriented Monitoring Waivers

[40 C.F.R 58 Appendix D 4.5(a)(ii)]

• EPA can grant waivers of required source-oriented monitors if State or Local can demonstrate that:

– Maximum Pb concentration will not exceed of 50% of the NAAQS (based on historical monitoring data, modeling, or other means).

• Modeling info at EPA’s Support Center for Regulatory Atmospheric Modeling (SCRAM) website at epa.gov/scram001

• AERMOD is the preferred model for near-field dispersion• EPA is creating a post-processing program that reads model

output and calculates rolling 3-month averages.• Model must demonstrate max concentration < 0.075μg/m3

• Ambient air means outside facility fence line provided that all of facility property is secured from public access

Source-Oriented Monitoring Waivers (cont.)

[40 C.F.R 58 Appendix D 4.5(a)(ii)]

• Waiver request letters must be submitted with Network Plans due July 1st.

• All required sources must have either:– Signed monitoring

waiver, or– Pb monitor operating

by January 1, 2010.

Ambient Monitoring Methods• Primary indicator is lead in total suspended particles (Pb-TSP), due

to evidence that lead particles of all sizes pose health risks.

• Pb-PM10 can be used instead of Pb-TSP monitoring if:– Lead is not expected to occur as large particles; and– Lead concentrations are not expected to have three-month averages greater

than or equal to 0.1 μg/m3 • If a Pb-PM10 monitor measures to 0.1 μg/m3 or above, then Pb-TSP monitor

must be installed within six months• Pb- PM10 measurements greater than the NAAQS violate the standard.• Anticipate that Pb-PM10 can be used at most or all of the population-oriented

sites.• Note that Pb-PM10 data is considered surrogate data for Pb-TSP, and

cannot be used to demonstrate attainment with the NAAQS.

Pb-TSP Sampling

• High-volume TSP (total suspended particulate matter) sampling

• 40 CFR Part 50, Appendix B• Federal reference method

(FRM) approved in 1983 for collecting TSP

• Collects particles up to 25-50 μm• Flow rate of 1600 liters per

minute (LPM) resulting in total 24-hour sample volume of ~2400 cubic meters

• Typically samples on 8x10-inch glass fiber or quartz filters

Sampling Methods: Pb-PM10

• Low-volume PM10 sampling– Analysis: 40 CFR Part 50, Appendix

Q– PM10c Sampler FRM: 40 CFR Part 50,

Appendix O

• Collects particles less than or equal to 10 micrometers

• Low-volume sampling at flow rates of 16.7 LPM resulting in total 24-hour sample volume of ~24 m3

• Any approved FRM/FEM PM10c sampler can be used when coupled with the FRM Pb-PM10 analysis.

Additional Resources

• Lead monitoring information and NAAQS Q&A documents: http://www.epa.gov/ttn/amtic/pb-monitoring.html

• Regulatory actions related to the Lead NAAQS including text of the final rule: http://epa.gov/air/lead/actions.html

• 2005 National Emissions Inventory (NEI) data for lead sources: ftp://ftp.epa.gov/EmisInventory/2005_nei/lead_summaries/